Hemoglobin Bart's Hydrops Fetalis Research Articles

Ten years' experience in prenatal diagnosis of α-thalassemia in a municipal hospital and retrospective analysis of ultrasonic abnormalities.

This study reviewed and analyzed the prenatal diagnosis experience of thalassemia in our center over the past decade and the abnormal ultrasonic characteristics of fetuses with hemoglobin (Hb) Bart's hydrops fetalis. Pregnant women and their partners who tested positive for α0-thalassemia or were diagnosed with thalassemia intermedia (HbH diseases) underwent genetic counseling, and a prenatal diagnostic procedure for α-thalassemia was recommended. Ultrasonography was performed before prenatal diagnosis. Invasive prenatal α-thalassemia diagnosis and ultrasonography were performed in 1049 patients at risk for Hb Bart's hydrops fetalis syndrome at our hospital from 2012 to 2021. Chorionic villus sampling (CVS) was performed in 58 cases (5.5%), amniocentesis in 902 cases (86%), and cordocentesis in 89 cases (8.5%). Hb Bart's hydrops fetalis syndrome was diagnosed in 280 fetuses. The most common body cavity effusion was pericardial effusion, ascites, and fetal systemic edema. The extensive experience at our center shows that carrier screening, molecular diagnostics, genetic counseling, and prenatal diagnosis are effective measures to prevent Hb Bart's hydrops fetalis syndrome. The ultrasonographic abnormalities in fetuses with Hb Bart's hydrops are mainly caused by an increase in cardiac output, which leads to the body cavity effusion from various organs.

Epidemiology of birth defects based on a birth defects surveillance system in southwestern China and the associated risk factors.

Birth defects (BDs) are associated with many potential risk factors, and its causes are complex. This study aimed to explore the epidemiological characteristics of BDs in Guangxi of China and the associated risk factors of BDs. BDs data of perinatal infants (PIs) were obtained from the Guangxi birth defects monitoring network between 2016 and 2020. Univariate Poisson regression was used to calculate the prevalence-rate ratios (PRR) to explore the changing trends of BDs prevalence by year and the correlation between the regarding of characteristics of BDs (including infant gender, maternal age, and quarter) and BDs. Clinical characteristics of PIs with BDs and general characteristics of their mothers were documented, and Spearman correlation analysis was used to explore the potential associated risk factors of BDs. Between 2016 and 2020, 44,146 PIs with BDs were monitored, with an overall BDs prevalence of 121.71 (95% CI: 120.58-122.84) per 10,000 PIs, showing a significant increase trend (PRR = 1.116, 95% CI: 1.108-1.123), especially the prevalence of congenital heart defects (CHDs) that most significantly increased (PRR = 1.300, 95% CI: 1.283-1.318). The 10 most common BDs were CHDs, polydactyly, congenital talipes equinovarus, other malformation of external ear, syndactyly, hypospadias, cleft lip with cleft palate, cleft lip, hemoglobin Bart's hydrops fetalis syndrome (BHFS), and congenital atresia of the rectum and anus. BDs were positively correlated with pregnant women's age (R = 0.732, P < 0.01) and education level (R = 0.586, P < 0.05) and having pre-gestational diabetes mellitus (PGDM)/gestational diabetes mellitus (GDM) (R = 0.711, P < 0.01), while when the pregnant women had a family history of a dead fetus (R = -0.536, P < 0.05) and a birth of a fetus with BDs (R = -0.528, P < 0.05) were negatively correlated with BDs. A significant increase in the prevalence of BDs was detected between 2016 and 2020 in Guangxi, especially the prevalence of CHDs that most significantly increased. Older maternal age, higher maternal education level, and having PGDM before pregnancy or GDM in early pregnancy were the risk factors for BDs.

Optimizing transfusion therapy for survivors of Haemoglobin Bart's hydrops fetalis syndrome: Defining the targets for haemoglobin-H fraction and "functional" haemoglobin level.

Owing to the unique pathophysiology of anaemia in haemoglobin Bart's hydrops fetalis (HBHF), a transfusion strategy based on beta-thalassemia guidelines is suboptimal for chronically transfused HBHF patients. A more aggressive transfusion aimed at reducing the proportion of non-functional HbH and improving the "functional" haemoglobin (f-Hb) can lead to reduced haemolysis and improved tissue oxygenation. However, the optimal transfusion targets for these parameters are not yet defined. In this retrospective, longitudinal study on four chronically transfused patients with HBHF, we used receiver operating characteristic curves to find a pre-transfusion f-Hb of 106g/l and a HbH of 16.1% to be the optimal thresholds to achieve a normal soluble transferrin receptor and lactate dehydrogenase, respectively.

Placental transcriptome sequencing combined with bioinformatics predicts potential genes and circular RNAs associated with hemoglobin Bart's hydrops fetalis syndrome.

Hemoglobin Bart's hydrops fetalis syndrome (BHFS) is the most severe form of α-thalassemia. Histological alternations can be observed in placenta, but placental transcriptome profile and circular RNAs have not been studied in this disease. The aim of this study was to define the placental transcriptional changes and find relevant circular RNAs in BHFS. We performed high-throughput RNA sequencing to detect placental samples from fetuses affected by BHFS (n=5) and normal fetuses (NF, n=5), quantitative reverse transcription polymerase chain reaction (RT-qPCR), and Sanger sequencing to validate the differentially expressed circRNAs and their potentially related miRNAs (BHFS, n=22; NF, n=11). Bioinformatics methods were performed for further analysis. Our results showed 152 differentially expressed genes (DEGs), 112 circRNAs, and 45 microRNAs that were differentially expressed. DEGs were found to be involved in Gene Ontology terms related to gas transport, cell adhesion, oxidative stress, organ development, hemopoiesis, and others. RT-qPCR results showed that hsa_circ_0003961 and hsa_circ_0006687 were upregulated (p < 0.05). The competing endogenous RNA and co-expression networks showed that hsa_circ_0003961 and hsa_circ_0006687 were connected with 3 miRNAs and some DEGs, including cell adhesion genes (e.g., CLDN19), hemoglobin related genes (e.g., SOX6 and HBZ) and angiogenesis related genes (e.g., EPHB2). Downregulations of hsa-miR-1299 and hsa-miR-625-5p in ceRNA network were also validated by RT-qPCR. Gene set enrichment analysis results for the two circRNAs showed that some gene sets associated with cell adhesion, hematopoietic system and apoptosis were significantly enriched. Our study characterized the placental transcriptome of BHFS. The circRNAs hsa_circ_0003961 and hsa_circ_0006687 in placenta may be relevant to BHFS.

Serum Ferritin Underestimates Liver Iron Concentration in Patients with Homozygous Alpha-0 Thalassemia

Background: Homozygous α0-thalassemia (Hemoglobin Bart's hydrops fetalis, HBHF) results from deletion of all α-globin genes. Similar to patients with transfusion-dependent beta-thalassemia (TDT-β), survivors of HBHF require life-long transfusions which over time will inevitably lead to significant tissue iron overload (IO). We have recently reported that the underlying disease process in HBHF is different from that of TDT-β (Amid A. et al. Blood, 2016). Unlike TDT-β, hemolysis is the major pathophysiologic process in HBHF and chronically transfused HBHF patients continue to have significant erythropoietic activity and tissue hypoxia (with increased serum erythropoietin) due to the indegenous nonfunctional hemoglobin-H. In addition, almost all survivors of HBHF would have commenced their transfusion therapy in-utero, potentially resulting in earlier IO compared to their TDT-β counterparts. Considering these differences, we hypothesized that the pattern of IO in patients with HBHF would likely differ from those with TDT-β.Methods: Following research ethics board approval, we retrospectively collected longitudinal data on transfusion and chelation history, serum ferritin, and liver iron concentration (LIC) measured by MRI or biopsy, in 7 HBHF (5 males; mean age: 7.3 years) and 14 TDT-β (8 males; mean age: 11.1 years) patients. None of the HBHF or TDT-β patients were splenectomized. Corresponding pairs of serum ferritin and LIC assessment (defined as measurements of not more than two weeks apart with no transfusions in between) were used to calculate ferritin-to-LIC ratios. All patients were treated with the same transfusion protocol to maintain pre-transfusion hemoglobin of >90 g/L and LIC of <5 mg/g of dry liver weight, until 2014. Since April 2014, five patients with HBHF have been commenced on a more aggressive transfusion strategy to decrease the nonfunctional HbH, suppress erythropoiesis, increase tissue oxygenation, and reduce hemolysis. We used linear mixed models to assess the associations between serum ferritin, LIC, and ferritin-to-LIC ratio with age, disease type (HBHF vs. TDT-β), chelation type, and method of LIC assessment. Correlations within a subject and between different ages were effectively accounted for in this model.Results: At 12 month of age, chelation-naïve HBHF patients had significantly higher serum ferritin level reflecting earlier IO compared to chelation-naïve TDT-β patients [1242.4 μg/dL (SD 419.4) vs. 418.3 μg/dL (SD 113.3), p<0.001]. On longitudinal assessments in both chelated HBHF and TDT-β patients, ferritin was significantly correlated with LIC (ρ = 0.88, p <0.001 and ρ = 0.46, p <0.001, respectively). Serum ferritin was significantly lower in HBHF vs. TDT- β [849 μg/dL (SD 573) vs. 2036 μg/dL (SD 1495), p<0.001] but there was no difference in LIC between the two groups [9.68 mg/g (SD 5.73) vs. 8.63 mg/g (SD 7.99), p=0.48]. Consequently, HBHF patients had significantly lower ferritin-to-LIC ratios [86.8 (SD 33.2) vs. 308.5 (SD 182.4), p<0.0001]. In addition, in the HBHF patients, serum ferritin-to-LIC ratio was corrolated with reticulocyte count (ρ = 0.41, p <0.042). In two mixed model analyses that included age, disease type, and method of LIC assessement or chelation type as variable of interset, disease type remained a highly signifiant predictor of serum ferritin-to-LIC ratio (p<0.0001). However, after the implementation of aggressive transfusion strategy (and suppression of erythropoeitic activity and improvement of tissue oxygenation) in HBHF patients, ferritin-to-LIC ratios were significantly higher [304.2 (SD 121.5) vs. 86.87 (SD 33.2), p=0.0003], becoming similar to ratios in TDT-β patients (p=0.88).Conclusion: Patient with HBHF are at-risk of significant IO early in life which poses potential challenges with iron chelation at an early age. Furthermore, in these patients, ferritin significantly underestimates LIC. This finding has important implications for clinical care and surveillance of IO in these patients, especially in areas with limited resources where non-invasive assessement of LIC (MRI) may not be widely available. The lower ferritin-to-LIC ratio observed in HBHF patients and its relation to erythropoietic activity indirectly suggest that in addition to transfusional iron loading, increased gastrointestinal absorption of iron due to suppressed hepcidin may also contribute to siderosis in these patients. DisclosuresNo relevant conflicts of interest to declare.

Outcomes of allogeneic transplantation for hemoglobin Bart's hydrops fetalis syndrome in Hong Kong.

Hemoglobin Bart's hydrops fetalis syndrome (BHFS) was once considered a fatal condition universally. Medical advances over the past three decades have resulted in increasing numbers of BHFS survivors. This retrospective review summarized local territory-wide experience and outcomes of BHFS patients who received allogeneic hematopoietic stem cell transplantation (HSCT) in Hong Kong. All BHFS patients who underwent allogeneic HSCT in Hong Kong, either in one of the two former pediatric transplant centers (Queen Mary Hospital and Prince of Wales Hospital) on or before 2019 or in the single territory-wide pediatric transplant center (Hong Kong Children's Hospital) since 2019, from January 1, 1996, till December 31, 2020, were included. Basic demographic data, perinatal history, transplant details, long-term outcomes, and morbidities were reviewed. Total five allogeneic HSCT were performed in two males and three females at a median age of 22months, which include one 8/8 matched-sibling bone marrow transplant, one 5/6 matched-sibling cord blood transplant with HLA-DR antigenic mismatch, two 12/12 matched-unrelated peripheral blood stem cell transplant (PBSCT), and one haploidentical PBSCT with TCRαβ/CD45RA depletion from maternal donor. Neutrophil and platelet engrafted (>20×109 /L) at a median of 15 and 22days, respectively. All achieved near full donor chimerism at 1month. All patients survived and remained transfusion-independent without significant morbidities with median follow-up duration of 10years. To conclude, local data demonstrated favorable outcome of allogeneic HSCT for BHFS patients, but sample number is small. Non-directive approach in counseling and international collaboration is recommended.

Noninvasive Prenatal Detection of Hemoglobin Bart Hydrops Fetalis Via Maternal Plasma Dispensed With Parental Haplotyping Using the Semiconductor Sequencing Platform

(Abstracted from Am J Obstet Gynecol 2020;222:185.e1–185.e17) Hemoglobin Bart's hydrops fetalis syndrome (Hb Bart's) is a common inherited genetic disease in the south of China and Southeast Asia. Couples who are both carriers of the Southeast Asian type of α-thalassemia gene deletion have a 25% risk of having a pregnancy affected with Hb Bart's as a result of autosomal recessive inheritance.

Noninvasive prenatal detection of hemoglobin Bart hydrops fetalis via maternal plasma dispensed with parental haplotyping using the semiconductor sequencing platform

Thalassemia is one of the most common monogenetic diseases in the south of China and Southeast Asia. Hemoglobin Bart's hydrops fetalis syndrome was caused by a homozygous Southeast Asian deletion (-/-) in the HBA gene. Few studies have proved the potential of screen for Bart's hydrops fetalis using fetal cell-free DNA. However, the number of cases is still relatively small. Clinical trials of large samples would be needed. In this study, we aimed to develop a noninvasive method of target-captured sequencing and genotyping by the Bayesian method using cell-free fetal DNA to identify the fetal genotype in pregnant women who are at risk of having hemoglobin Bart hydrops fetalis in a large-scale study. In total, 192,173 couples from 30 hospitals were enrolled in our study and 878 couples were recruited, among whom both the pregnant women and their husbands were detected to be carriers of Southeast Asian type (-/αα) of α-thalassemia. Prenatal diagnosis was performed by chorionic villus sampling, amniocentesis, or cordocentesis using gap-polymerase chain reaction considered as the golden standard. As a result, we found that the sensitivity and specificity of our noninvasive method were 98.81% and 94.72%, respectively, in the training set as well as 100% and 99.31%, respectively, in the testing set. Moreover, our method could identify all of 885 maternal samples with the Southeast Asian carrier and 36 trisomy samples with 100% of sensitivity in T13, T18, and T21 and 99.89% (1 of 917) and 99.88% (1 of 888) of specificity in T18 and T21, respectively. Our method opens the possibility of early screening for maternal genotyping of α-thalassemia, fetal aneuploidies in chromosomes 13/18/21, and hemoglobin Bart hydrops fetalis detection in 1 tube of maternal plasma.

Potential new approaches to the management of the Hb Bart's hydrops fetalis syndrome: the most severe form of α-thalassemia.

The α-thalassemia trait, associated with deletions removing both α-globin genes from 1 chromosome (genotype ζ αα/ζ--), is common throughout Southeast Asia. Consequently, many pregnancies in couples of Southeast Asian origin carry a 1 in 4 risk of producing a fetus inheriting no functional α-globin genes (ζ--/ζ--), leading to hemoglobin (Hb) Bart's hydrops fetalis syndrome (BHFS). Expression of the embryonic α-globin genes (ζ-globin) is normally limited to the early stages of primitive erythropoiesis, and so when the ζ-globin genes are silenced, at ∼6 weeks of gestation, there should be no α-like globin chains to pair with the fetal γ-globin chains of Hb, which consequently form nonfunctional tetramers (γ4) known as Hb Bart's. When deletions leave the ζ-globin gene intact, a low level of ζ-globin gene expression continues in definitive erythroid cells, producing small amounts of Hb Portland (ζ2γ2), a functional form of Hb that allows the fetus to survive up to the second or third trimester. Untreated, all affected individuals die at these stages of development. Prevention is therefore of paramount importance. With improvements in early diagnosis, intrauterine transfusion, and advanced perinatal care, there are now a small number of individuals with BHFS who have survived, with variable outcomes. A deeper understanding of the mechanism underlying the switch from ζ- to α-globin expression could enable persistence or reactivation of embryonic globin synthesis in definitive cells, thereby providing new therapeutic options for such patients.

Outcomes and morbidities of patients who survive haemoglobin Bart's hydrops fetalis syndrome: 20-year retrospective review.

Haemoglobin Bart's hydrops fetalis syndrome was once considered a fatal condition. However, advances over the past two decades have enabled survival of affected patients. Data relating to their morbidities and outcomes will help medical specialists formulate a management plan and parental counselling. All babies with the syndrome who survived beyond the neonatal period and were subsequently managed long-term in eight public hospitals in Hong Kong from 1 January 1996 to 31 December 2015 were included. Patient and parent characteristics, antenatal care, reasons for continuation of pregnancy, intrauterine interventions, perinatal course, presence of congenital malformations, stem-cell transplantation details, and long-term neurodevelopmental outcomes were reviewed. A total of nine patients were identified, of whom five were female and four male. The median follow-up duration was 7 years. All were Chinese and were homozygous for the Southeast Asian α-thalassaemia deletion. Five of the nine mothers received antenatal care at a public hospital and opted to continue the pregnancy after antenatal diagnosis and counselling. Despite intrauterine transfusions, all babies were born with respiratory depression and required intubation and mechanical ventilation during the neonatal period. Hypospadias was identified in all four male infants. Growth retardation, global developmental delay, and residual neurological deficits were noted in two-thirds of the patients. Haematopoietic stem-cell transplantation was performed in two patients, who became transfusion-independent. Survival of patients with Bart's hydrops fetalis syndrome is possible but not without short- and long-term complications; local epidemiology is comparable to that documented for an international registry. Detailed antenatal counselling of parents with a non-judgemental attitude and cautious optimism are imperative.

Alpha thalassemia deletions found in suspected cases of beta thalassemia major in Pakistani population.

Background & Objective:Alpha (α) thalassemia is a hereditary disorder and is caused by deletions or mutations in globin genes. It is present in two clinically significant forms: hemoglobin Bart hydrops fetalis (Hb Bart) syndrome and hemoglobin H (HbH) disease. It is highly prevalent in South-East Asia or Mediterranean countries. The most common deletion reported in alpha thalassemia in Pakistani population was –α3.7 with a frequency of 8.3%, and the rare forms were –α4.2 (0.2%) and αααanti3.7 (0.9%). In our study, diagnosis of severe anemia cases without any α and β mutations or deletions were made by using extended alpha thalassemia deletions panel. The main objective of this study was to determine the prevalence and to study the spectra of alpha thalassemia gene deletions in beta thalassemia patients with the use of an extended panel including −−SEA, −−FIL, −−MED, −−20.5, −−THAI in addition to –α3.7, –α4.2 & -αααanti3.7.Methods:The samples were collected in ethylenediaminetetraacetic acid (EDTA) vacutainers. A total of 156 samples were analyzed for alpha thalassemia mutations. This cohort included 121 samples of beta thalassemia major, nine samples of beta thalassemia minor and 26 without any evidence of beta thalassemia mutations. DNA was extracted with Qiagen extraction kit. The primers for determination of different subsets of alpha thalassemia deletions were included. PCR amplification was performed and result interpreted on agarose gel.Results:Co-inheritance of alpha thalassemia (–α3.7, –α4.2) with homozygous beta thalassemia was detected in 30% cases of studied cohort (37 out of 121). The most common found was –α3.7 deletion (35/37) as single/double deletions or in combination with -αααanti3.7. In undiagnosed cases screened for beta thalassemia major, we found Mediterranean (–αMED) deletion at specifically 875 bp on agarose gel. This is distinctive finding in case of detecting –αMED instead of any other deletion from Pakistan.Conclusion:Alpha thalassemia deletions (–α3.7, –α4.2) are the common co-inherited deletions found in beta thalassemia major patients. On the basis of results, we propose an extended alpha thalassemia genetic mutation panel should be used for screening of children presenting with anemia with suspicion of haemoglobinopathy.

Prenatal diagnosis of Thailand deletion of α-thalassemia 1 families

To conduct analysis and prenatal diagnosis on 11 couples carrying Thailand deletion (--(THΑI)) α-thalassemia 1, so as to provide information for clinical genetic counseling on α-thalassemia 1. Altogether 11 Thailand deletion (--(THΑI)) α-thalassemia 1 families were collected from Fujian Maternal and Children Health Hospital from May 2009 to September 2015. Gap-polymerase chain reaction (gap-PCR) and reverse dot blot (RDB) technology were used to detect the thalassemia mutations in the couples and fetuses. In one family, Thailand deletion α-thalassemia 1 was detected in both the pregnant woman and her husband. In 10 families, Thailand deletion α-thalassemia 1 was detected in either the pregnant women or the husband, while the spouses had α-thalassemia heterozygote (1 combined with β thalassemia heterozygote). Thailand deletion α-thalassemia 1 family members all had lower mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH). In prenatal diagnosis of the 12 fetuses, 4 fetuses were found with hemoglobin(Hb) Bart's hydrops fetalis syndrome, 5 were with α-thalassemia heterozygote, and 3 were normal. For couples with positive hematological phenotype but normal results in routine genetic examination of α-thalassemia, attention should be paid especially for with a history of having babies of hydrops fetalis syndrome or hemoglobin H disease. It is necessary to consider the possibility of the rare Thailand deletion (--(THΑI)) α-thalassemia 1. Prenatal diagnosis for high-risk families plays an important role.

Hemoglobin Bart hydrops fetalis: A model for studying vascular changes in placental hypoxia

IntroductionPlacental ischemia can be pre-placental (maternal), placental or post-placental (fetal), with corresponding changes in villous vasculature. Hydrops fetalis (HF) resulting from hemoglobin (Hb) Bart disease can serve as a model for intrauterine hypoxia, and placentas from such cases show a distinctive peripheral villous stromal myofibroblastic hypercellularity (PVSH). We hypothesized that Hb Bart disease, which results in profound fetal hypoxia, would lead to placental hypoxia on a post-placental basis. MethodsWe assessed villous vasculature using computerized morphometry, comparing placentas in 14 Hb Bart HF cases to 18 non-Hb Bart HF cases. Morphometric parameters were matched as closely as possible to those reported in the literature for comparison purposes. ResultsVillous vessels of Hb Bart HF showed significantly increased numbers of vessels (p = 0.001), longer vascular perimeter (p = 0.002), thickening of vascular endothelial layer (p = 0.038) and higher shape coefficient (p = 0.042) indicating a more branching pattern of vessels. In addition, placental villi of Hb Bart HF containing PVSH showed a longer vascular perimeter (p = 0.008) and narrower lumen (p = 0.002), with a higher shape coefficient (p = 0.03), in comparison to villi lacking PVSH. DiscussionContrary to expectations, the overall pattern of vascular changes in Hb Bart HF suggested multifactorial hypoxia: pre-placental, on the basis of the marked placentomegaly, compromising blood flow from uterine distention; placental, from hydropic villi causing a generalized diminished intervillous space; and post-placental from the greatly reduced capacity of Hb Bart to extract oxygen from the intervillous space. Standardized vascular morphometry will facilitate comparison between different conditions, for a better understanding of placental hypoxia.

Use of High-Performance Liquid Chromatography for Prenatal Diagnosis of a-Thalassemia (Hemoglobin Bart's) Hydrops Fetalis in Fetal Cord Blood Sample

The gold standard for prenatal diagnosis of α-thalassemia is mutational analysis of fetal cells by chorionic villous sampling or amniocentesis. However, these are time-consuming tests and thus, in the mid-trimester the diagnosis can be made expeditiously by percutaneous umbilical cord blood sampling with high-performance liquid chromatography (HPLC) analysis of the fetal hemoglobins. We present a case of Bart’s …

Validation of the immunochromatographic strip for α-thalassemia screening: a multicenter study

α(0)-Thalassemia occurs from a deletion of 2 linked α-globin genes and interaction of these defective genes leads to hemoglobin (Hb) Bart's hydrops fetalis, the most severe and lethal thalassemia syndrome. Identification of α(0)-thalassemia carriers is thus essential for the prevention and control program. An immunochromatographic (IC) strip test was developed for rapid screening of α(0)-thalassemia by testing for Hb Bart's in the blood samples using a specific monoclonal antibody against Hb Bart's. To evaluate its sensitivity and specificity, the IC strip test was assessed in a cohort with various thalassemia genotypes from 4 different laboratories in Thailand and Australia. The result showed 97% sensitivity in α-thalassemia carriers with 2 α-globin genes deletion and Hb H disease. This is, in particular, the useful rapid screening test for regions where β-thalassemia and homozygous Hb E are also common. Similar hematologic and Hb data make it impossible to address the concomitant inheritance of α(0)-thalassemia in these samples without polymerase chain reaction (PCR)-based techniques, leading to misdiagnosis of the risk of having Hb Bart's hydrops fetalis. However, α-globin genotyping should be carried out in samples with positive IC strip as positive reactivity was also observed in homozygous α(+)-thalassemia carriers who have 2 trans α-globin gene deletions. These results indicate that in combination with red blood cell indices, the IC strip test could rule out mass populations for further α(0)-thalassemia detection by PCR-based analysis. The Alpha Thal IC strip also has the potential to replace testing for Hb H inclusion bodies, as it appears to be more sensitive, specific, and less labor intensive.

A SIMPLE AND HIGHLY SENSITIVE ELISA FOR SCREENING OF THE α-THALASSEMIA-1 SOUTHEAST ASIAN-TYPE DELETION

Couples in which both partners carry the α-thalassemia-1 trait have a 25% risk of hemoglobin Bart's hydrops fetalis in each pregnancy. Identification of α-thalassemia-1 trait is, therefore, necessary in order to control this severe form of α-thalassemia. We have generated monoclonal antibodies specific to the ζ-globin chain without cross reaction with other globin chains. A simple and sensitive ELISA was developed by using poly-l-lysine to increase the protein binding to the ELISA plate. The developed poly-l-lysine pre-coated ELISA has a very high sensitivity (100%) and specificity (97%) for detection of carriers of α-thalassemia-1 with Southeast Asian-type deletion.

P02.13: Two unusual cases of haemoglobin Bart's hydrops fetalis screened negative on universal prenatal screening for thalassemia

<scp>P02</scp>.13: Two unusual cases of haemoglobin Bart's hydrops fetalis screened negative on universal prenatal screening for thalassemia

Molecular and hematological studies in a large cohort of α0-thalassemia in northeast Thailand: Data from a single referral center

α(0)-thalassemia is the most severe form of α-thalassemia alleles found among Southeast Asian and Chinese populations and can cause a fatal condition known as hemoglobin Bart's hydrops fetalis and hemoglobin H disease. In order to provide the molecular epidemiological characteristic of α(0)-thalassemia in northeast Thailand, a total of 12,525 blood specimens referred to our center at Khon Kaen University in northeast Thailand during October 2008 to January 2012 were studied. Hematological parameters were recorded and DNA deletions causing α(0)-thalassemia were examined by PCR related techniques. Among 12,525 samples examined, α(0)-thalassemia alleles were identified in 1,873 (15.0%) samples, including 1855 (14.8%) cases with Southeast Asian (--(SEA)) deletion and 18 cases (0.2%) with THAI deletion (--(THAI)). As many as twenty genotypes were encountered. Hb profiles and hematological parameters were comparatively presented. Data on prevalence, molecular features and phenotypic expression of α(0)-thalassemia should prove useful in a carrier screening and a prevention and control program of this common genetic disorder in the region.

Clinical Manifestations of -Thalassemia

α-Thalassemia mutations affect up to 5% of the world's population. The clinical spectrum ranges from an asymptomatic condition to a fatal in utero disease. Hemoglobin H disease results from mutations of three α-globin genes. Deletional forms result in a relatively mild anemia, whereas nondeletional mutations result in a moderate to severe disease characterized by ineffective erythropoiesis, recurrent transfusions, and growth delay. Hemosiderosis develops secondary to increased iron absorption, as well as transfusion burden. Hemoglobin Bart's hydrops fetalis is usually a fatal in utero disease caused by the absence of α genes. Population screening to identify at-risk couples is essential. Affected pregnancies result in severe fetal and maternal complications. Doppler ultrasonography with intrauterine transfusion therapy may improve the fetal prognosis but creates ethical challenges for the family and health providers.

Alfa Thalassemia Intermedia (HbH disease): How the New Information Provided by the Routine Hematology Analysers May Help in Its Differential Diagnosis or Flagging

AbstractAbstract 5180Alpha-thalassemia (α-thalassemia) has two clinically significant forms: hemoglobin Bart hydrops fetalis (Hb Bart) syndrome and hemoglobin H (HbH) disease. HbH disease is characterized by microcytic hypochromic hemolytic anemia, hepatosplenomegaly, mild jaundice, and sometimes thalassemia-like bone changes. Diagnostic of Alfa Thalassemia:Classic testing for α-thalassemia includes: hematologic testing of red blood cell indices, peripheral blood smear, supravital stain to detect RBC inclusion bodies, and qualitative and quantitative hemoglobin analysis. HBA1, the gene encoding α1-globin, and HBA2, the gene encoding α2-globin, are the two genes most commonly associated with α-thalassemia. Molecular genetic testing of HBA1 and HBA2 detects deletions in about 90% and point mutations in about 10% of affected individuals. Objective:Recently have been developed new parameters and information in the new automated hematology analyzer called DxH8008™ from Beckman Coulter as @MSCV, @RSF, @MAF, @LHD% and many morphological parameters for RBC and Reticulocytes calles Cell Population Data. All this parameters may be used to create flagging for laboratory use only (LUO) or Research use only (RUO). The purpose of this study is to investigate the possible use or utility of this new information for the screening/flagging of Alfa Thalassemia. Patient and Methods:We have collected 129 patients with Alfa Thalassemia Intermedia (HbH disease). All of them were confirmed by red cell morphology, Hgb Electroforesis, cromatography in liquid phase in human whole blood for the determination of Hemoglobin A2, F, A1c, and identification of abnormal hemoglobins and DNA analysis (DNA Analysis by GAP-PCR). We have compared these patients with a control group (184 individuals) and with other anemias (see Table 1).Table 1DiagnosticnNON BETA (control)184HbH (alfa thalasemia intermedia) (study group)129Alfa Thalassemia Heterozygous46Beta Thalassemia Trait30Hereditary Spherocytosis28Iron Deficiency Anaemia22Thalassemia intermedia (Beta-Thal Interm)18microdrepanocitosi (Beta-S)8Blackfan-Diamond Anemia3Dyserithropoietic Anaemia type I (CDA I)3Sickle cell anaemia3Piruvate-Kinase deficiency3IRIDA iron-refractory iron deficiency anemia3Beta Thalassemia major3Fanconi's Anaemia2Dyserithropoietic Anaemia type II (CDA II)2Hyporegenerative anemia2Megaloblastic Anemia1Piruvate-Kinase deficiency Splenectomized1Hemoglobinopaty (Taybe) + α- thalassemia1Hemoglobinopaty hyperunstable (Hb Cagliari)1Hemoglobinopaty Koln1Acute Lymphoblastic Leukemia (ALL)1Pyropoikilocytosis1Evans's Syndrome1 Results:Using ROC analysis, the best parameters differentiating the HbH Disease from the normals were: RDW (AUC 1. 000), @LHD(AUC 1. 000), @MAF(AUC 1. 000), @MCNRET (AUC 1. 000), MCV (AUC 0. 999), @MCRET (AUC 0. 999), @RSF (AUC 0. 998), HGB (AUC 0. 996), @MSCV (AUC 0. 995).Using ROC analysis, the best parameters differentiating the HbH Disease from other anemias (excluding normals) were: @LHD(AUC 0. 957), @MCNRET (AUC 0. 946), @MCRET (AUC 0. 902), @MAF(AUC 0. 873), MCV (AUC 0. 869).Using logistic regression we found a discrminant function that permits to differentiate/flag perfectly the patients with HbH disease from other anemias, and of course from normals: AUC 0. 996) Sensitivity: 91. 47% Specificity 94. 68% with a percent of cases correctly classified of: 93. 67 %. Disclosures:Simon-Lopez:Beckman Coulter: @LHD, @MAF, @RSF, @LHD, @MAF, @RSF Patents & Royalties, Employment. Di Gaetano:Instrumentation Laboratory spa: Work for a distributor of Beckman Coulter Instruments in Italy Other. Galanello:Novartis: Research Funding, Speakers Bureau; Apopharma: Research Funding, Speakers Bureau; Ferrokin: Research Funding.